Static electricity indicator



June 12, 1951 R. c. WEBSTER 2,556,458

s'm'nc ELECTRICITY INDICATOR Filed Feb. 9, 1948 I INVJZENTIOR.

0 ATTORWE Patented June 12, 1951 UNITED STATES STATIC ELECTRICITY INDICATOR Raymond C. Webster, Kansas City, Mo., ass'ignor to W. E. Anderson, Inc., a corporation of Mis souri Application February 9, 1948, Serial No. 7,212

1 Claim. 1

This invention relates to static electricity indicators, and more particularly to an electric device capable when placed in use, of positively detecting and indicating to the user thereof the presence of statical electricity in virtually any body.

It is a fundamental principle of electricity that when two bodies come into frictional contact with each other, static electricity is created in each of said bodies and this phenomenon is generally covered by the field of electrostatics. The presence of such static electricity, whether it consists of negative or positive charges, is oftentimes disadvantageous and many cases dangerous. The danger factor is most predominant in the field of medicine, particularly in zones of anesthesia where explosions are common because of aspark discharge of static electricity.

It is the primary object of this invention, therefore, to provide an inexpensive and easily operated relatively small portable device capable of quickly detecting and indicating the presence of static electricity in any body, to the end that such electrical charges may be subsequently removed in any of the manners well known to those skilled in the art.

The most important object of this invention is the provision of an indicator of static electricity having an electrical circuit provided wth means for indicating the intensity of current in such means in a device of the above mentioned characterw for reestablishing the normal intensity of the current in the electric circuit after a body has once been tested without first de-energizing the circuit.

-Other objects of this invention include the 4 arrangement of parts within a specially designed case for rendering the entire instrument portable and easily handled; the way in which the manual manipulatable parts thereof, as well as the visual indicating :means are conveniently disposed upon 2 the case and obviously the inner connection of electrical elements to render the device operable in themanner above set forth.

Other objects of this invention will be made clear or become apparent during the course of the following specification, reference being had to the accompanying drawing, wherein:

Fig. 1 is a top plan view of a static electric indicator made in accordance with the present invention.

Fig. 2 is a side elevational view thereof, parts of a side cover plate being broken away to reveal arrangement of parts.

Fig. 3 is a schematic wirin diagram showing the electrical assembly of the device; and

Fig. 4 is a schematic wiring diagram showing a modified form of electrical construction.

As above indicated, the presence of electrical charges taking the form of static electricity in various objects, including the human body, may in many instances be ver detrimental to an attempted result, particularly in the field of medicine. It becomes desirous, therefore, .to

have means for quickly and easily indicating ing room present in the body of the surgeon himself, in the instruments he might use, in the body of his patient, and elsewhere, cause fatal explosions when created in the presence of highly combustible gases.

Referring now more particularly to thedr'awing, the numeral Ill designates broadly a hollow case having a top wall I 2 and an opposed bottom wall provided with a number of feet l4 secured thereto. This case It! is also provided with opposed end walls and opposed side walls, one of the latter of which constitutes a plate l6 removably mounted by means of a number of screws or the like 20. An insulator 22 formed from porcelain or the like is secured directly to one of'the end walls of body It! and this insulator 22.ha s a central opening therethrough, not shown'ffor receiving an elongated rod '24 produced from any highly conductive material. The innermost end of this rod 34 terminates within the confines of case I0.

A milliammeter 26 or other means for measuring electrical current is mounted directly upon the wall l2 of case I0 and extends inwardly into case it as clearly indicated in Fig. 2 of the'drawing. A pair of switches 26 and 3B are also mounted upon the uppermost wall I2 of case ID, the switch 28 preferably being of the spring loaded type, said spring yieldably holdin such switch 28 normally open. The switch 30 is a conventional toggle type obtainable upon the open market. These switches 29 and 3D likewise extend below the innermost face of wall I2. An electron tube 32, and a pair of batteries 34 and 36 are also mounted within the case I!) in a manner indicated in Fig. 2.

Referring now to Fig. 3 of the drawing, the electrical connection between conductor 24, tube 32, meter 26, batteries 34 and 36 and switches 28 and 38, will be described. The electron tube 32 chosen for illustration is a conventional pentode having five electrodes in the usual manner. These electrodes include a filament or cathode 38 heated by current passing therethrough, an anode or plate 48, a control grid 42, a screen grid 44 and the usual suppressor grid 46. The control grid 42 of tube 32 is connected directly to the innermost end of conductor 2'4 by means of a .40 of tube 32 has no connection in the circuit,

grid 44 being closer to cathode 38 and serving as a plate.

As indicated in Fig. 3, the toggle switch 38 is interposed between the wires 58 and 6|] and when the switch 38 is closed a complete circuit is produced through filament 38 and battery 3d. The screen grid voltage is completed by wires 62, 64 and 54 joining the other side of battery 36 and the cathode 38. A wire 66 within the tube 32 joins cathode 38 and grid 46. A direct connection between grid 42 and cathode 38 is created when the switch 28 is closed by means of wire 44 a wire 68, closed switch 28, a resistor and wire 48.

In operation the toggle switch 32 is manually moved to the closed position, thereby energizing and heating filament 38, such energy being produced by the battery 34. Such closing of the switch also closes a circuit through tube 32, meter 26 and battery 36. Obviously the grid 42 controls the flow of negative electrons from filament 38 to grid 44 and thence to wire 58, meter 26, wire 52 to battery 36. The amount of such current flow depends on the difierence in voltage ment 38. The intensity of such electrical current flowing through the tube 32 as determined by the strength of .battery 36 will be indicated on the meter 26 immediately upon closing of switch 30.

As the device is moved to a position in close proximity to any body having static charges existing therein, such charges will be conducted through the rod 24 when the body is in inductive relationship to the outermost end of the conductor 24. If such charges within the body are negative, then such charges will cause like charges present in red 24 to be driven to grid Q2. The negative charges at grid 42 of tube 32 wili be repelled and not allowed to pass through the electric circuit toward meter 28. The intensity of .the current in such circuit will immediately decrease and such decrease of current will be indicated by meter 28. As soon as the device is moved away from the body having negative charges therein, the meter 25 will immediately return to the normal indication since the original intensity of the current in the electric circuit will be reestablished.

In the event that the conductor 24 is brought into contact with the body, such negative charges present therein will be conducted to the tube 32 and will build up to such an extent that the intensity of current in the circuit will remain diminished for a short period of time. In this event the needle of meter 26 will show a low intensity until such negative charges built up in the circuit bleed therefrom, whereupon the current will return to its normal intensity.

When such building up of negative charges occurs, the operator may reestablish the normal intensity of the current by merely closing switch 28. Closing of this switch 28 interconnecting grid 42 and filament 38 will equalize the negative charges between control grid 42 and filament 38. When switch 38 is again opened the intensity of the current will be reestablished and the device may again be used as above indicated.

The resistor is within the circuit above described f-or equalizing the static charges is of relatively high value to the end that when the switch 28 is closed, accidental contact of con.- ductor 24 with a high voltage charge will not cause damage.

In the event that the body being tested contains positive static charges or an absence of negative electrons, such charges when received by the conductor 24 by moving the latter into inductive relationship with the charged body, will attract the negative electrons at the control grid 42' of tube 32 increasing momentarily the intensity of the current through meter 26. This action will not continue however, because the reappearance of additional negative electrons at the control grid 42 will immediately decrease the intensity of the current to its normal flow.

It is to be noted that the small flashlight type battery 38 of approximately 1 volts may be easily changed from time to time Without the necessity of replacing battery 36. This battery 38 is preferably of approximately volts and will last a considerable eriod of time since the energization of filament is created by the small battery 34.

The wiring assembly shown in Fig. 4 is essentially the same as that first described with respect to Fig. with the exception that means is provided for using the device with alternating current. The direct current static charge is received by a conductor I58 having connection with a control grid 182 of an electron tube I84. A screen grid i855, a suppresser grid I82 and a plate I09 also form a part of tube I04 and grid I86 and plate 33 are connected directly to a milliammeter I I8. A transformer broadly designated by the numeral I I2 has a primary I I4 and a pair of secondary windings H8 and H8: The primary iial or" transformer H2 is connected by means of a pair of lead lines 2.3 and i22 to a suitable source of alternating current electrical energy, not shown. A switch i2 3 comparable to the switch 33 shown in Figs. 1 to 3 inclusive is interposed in lead line 22. A small lamp I26 electrically joined :to the lines I26 and I22 indicates when current is flowing into the transformer I I2, since this lamp i28 is interposed between the switch I23 and the primary H4 of transformer The screen grid voltage is obtained through the secondary winding I I8 of transformer H2 having 1 direct connection with a cathode I30 of tube I64,

A filament I28 for cathode I30 is heated through connection with secondary IIB of transformer II2, the cathode I30 and control grid I02 of tube I04 are joined by a line I32 having a switch I34 interposed therein, comparable to the switch 28 above described, and a high resistance I36. A resistor I38 interposed between meter I I0 and secondary II8 of transformer II 2 is chosen to control the intensity of the screen grid voltage as determined by the voltage produced by secondary winding I [8. It is clear that the arrangement set forth in Fig. 4 will operate precisely the same as that shown in Fig. 3 and may be used by plugging lines I20 and I22 in a conventional alternating current outlet.

As indicated at I2 in Fig. 3 and at I46 in Fig. 4, the entire circuit is suitably grounded for best results. This may be accomplished by a conductor that is separately attached to ground by the operator before use of the device, or a line joined to the case I0 if the latter is made from conductible material, whereupon the operator merely places the case In on such ground. 1

From the foregoing description it is apparent that a device has been produced that embodies all the objects and advantages above pointed out, and while preferred constructions, combinations and arrangements of parts have been shown, the right is reserved to make such changes as properly fall within the spirit and scope of the appended claim.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

A device for indicating the presence of static electricity, said device comprising a vacuum tube REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,919,215 Gunn July 25, 1933 1,938,136 Crew Dec. 5, 1933 2,145,866 Failla Feb. 7, 19.39 2,178,954 Dehmel Nov. 7, 1939 2,208,329 Morelock July 16, 1940 2,262,916 Boucke Nov. 18, 1941 2,267,820 Droz et a1 Dec. 30, 1941 2,449,068 Gunn Sept. 14, 1948 2,464,428 Alven et al Mar. 15, 1949 OTHER REFERENCES Publication Radio Amateurs Handbook, 1946,

page 412. Published by A.R.R. League Inc., Connecticut. Page 412. 

